Oven-thermometer



-H. R WHITTIER. 0VEN THERMOMETER. APPLICATION FILED DEC. 3| 1920 31. ,38Q,621 a Patented. J 11116 7, 1921 the ends of the arms 6, and

in the end of the leg 8. The perforated ends- THERMOMETER COMPANY, 0F PLYMOUTH,

CONNECTICUT.

Specification of Letters Patent.

CONNECTICUT, A CORPORATION OF OVEN-THERMOIITETER.

ratentea June a, rear.

Application filed December 3, 1920. Serial No. e27,95c.

To all whom it may concern Be it known that 1, Homer. R. WHITTIER, a citizen of the United States, residing at Plymouth, in the county of Litchfield and State of Connecticut, have invented a new and useful Improvement in Oven-Thermometers, of which the following is a specification.

This invention relates to the construction of oven thermometers of the type illustrated and described in United States Letters Patent No. 1,151,638, August 31, 1915. 1

The object of this invention is to lessen the cost of manufacture and at the same time produce a thermometer which is durable, easily repaired when necessary, and more sensitive and less liable to error than prior thermometers of the type mentioned.

This object is attained by mounting all of the active elements,-the pointer arbor bearing the yoke and the thermoresponsive fingers which oscillate the yoke as they warp under the various temperature changes,- upon a single-piece, cheaply formed frame of good heat conducting material and thus producing an easily duplicated operative unit with the arbor, yoke and fingers always in the same exact relations, which can be readily attached in correct position to the back plate of the casing in which it is to be used.

In the accompanying drawings Figure 1 shows a front view of a thermometer constructed according to this invention, with the cover and dial omitted. Fig. 2 shows a transverse section on the plane indicated by the dotted line 22 on Fig. 1. Fig. 3 shows a rear view of the operative unit removed from the casing. Fig. 4: is a plan of the supporting frame blank.

These thermometers usually have a case comprising a cylindrical shell 1 and a back plate2 formed of thin sheet metal, the shell being designed to fit an opening in the wall of an oven and the plate to be fastened to the inner wall of the oven about the opening. In carrying out this invention a substantially T-shaped frame .is stamped from good heat conducting sheet metal, with perforations 3 in the head 4., perforations 5 in a perforation 7 of the arms are bent up at right angles and the perforated end of the leg is offset so as to extend in a plane parallel with the plane of the head of the frame.

The ends of the fingers 9 of common thermoresponsive metal are fastened by rivets 10 to the bent-up ends of the frame arms and the arbor 11 bearing the yoke 12 with which the free ends of the thermo fingers are engaged is passed through the perforation 7 in the plate. This operative unit 1s fastened to the back plate of the case with the lower end of the arbor set in the bushmg 1 1, by rivets 13 that are passed through the perforations 3 in the frame. The indicating pointer 15 is applied to the arbor after the parts are assembled in the case.

With the thermoresponsive arms and the arbor with the'yoke supported by the single frame which is fastened to the back plate of the casing, the cylindrical shell can be made of much thinner metal and can be made considerably lower than the shells of the prior thermometers in which some of the supporting elements are secured to the shells. The employment of the single supporting frame enables the parts to be located with great exactness, the responsive fingers and yoke to be correctly adjusted, and the arbor to be properly centralized without the employment of highly skilled labor and the exercise of extreme care in assembling parts. Furthermore, the frame with considerable area in close contact with the back plate of the case that is in the oven the temperature of which is to be indicated, readily conducts the heat uniformly to both thermo fingers so that they respond with a high degree of sensitiveness to the varying changes of temperature in the oven.

The invention claimed is 1. An even thermometer having a back plate, a frame secured to said back plate, an

arbor carrying a yoke rotatably supported,

by a bearing in said frame, and an end bearing in said back plate and. thermoresponsive fingers secured to said frame and engaging the ends of the yoke on the'arbor.

2. An oven thermometer having a back plate, a T-shaped frame secured to said back plate, a pointer arbor bearing a yoke rotatably supported by the leg of the frame, and an end bearing in said back plate and thermoresponsive fingers secured to the arms of the frame and engaging the ends of the yoke on the arbor.

3. An oven thermometer having a case comprising a cylindrical shell and a back plate, a T-shaped frame With an offset leg and upturned arms secured to said back plate, a pointer arbor bearing a yoke rotatably supported by the offset leg of the frame, and an end bearing in said back plate and thermoresponsive fingers secured to the upturned ends of the arms of the frame and 10 engaging the ends of the yoke on the arbor.

HORACE R, WHITTIERQ 

